Frequency-dependent nanomechanical profiling for medical diagnosis

• Santiago D. Solares and
• Alexander X. Cartagena-Rivera

Beilstein J. Nanotechnol. 2022, 13, 1483–1489, doi:10.3762/bjnano.13.122

• the AFM analysis for a viscoelastic material needs to be expressed in the appropriate physical quantities, namely the retardance or relaxance of the material or equivalent frequency-dependent quantities [15][16][17]. These are rich, transferrable quantities that offer much more detailed information

A new method for obtaining model-free viscoelastic material properties from atomic force microscopy experiments using discrete integral transform techniques

• Berkin Uluutku,
• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2021, 12, 1063–1077, doi:10.3762/bjnano.12.79

• assumptions (see Figure 1). These transfer functions are the viscoelastic relaxance and retardance, where the relaxance describes the time response of a viscoelastic material to a unit impulse excitation (Dirac delta function) of strain and the retardance describes the response of the material to an impulsive

• functions). More specifically, the stress at a given instant depends on the total previous history of strain and vice versa [13]. This history dependence is often expressed in the form of convolution integrals: where Q(t) and U(t) are known as relaxance and retardance, respectively. As already stated

• , relaxance and retardance describe the time response of a viscoelastic material to a unit impulse excitation (Dirac delta function) of either strain or stress, respectively [13]. Theoretically, knowledge of Q(t) or U(t) fully characterizes the viscoelastic behavior of the material, so we refer to them as

Correction: Extracting viscoelastic material parameters using an atomic force microscope and static force spectroscopy

• Cameron H. Parvini,
• M. A. S. R. Saadi and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2021, 12, 137–138, doi:10.3762/bjnano.12.10

• ). Similarly, it is stated that the loss modulus (E″) and loss compliance (J″) are inverses of one another (Equation 11). However, it is the relaxance (Q) and retardance (U) that are inverses of one another in the Laplace domain (not in the time domain), leading to a more complex relationship between the

On the frequency dependence of viscoelastic material characterization with intermittent-contact dynamic atomic force microscopy: avoiding mischaracterization across large frequency ranges

• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2020, 11, 1409–1418, doi:10.3762/bjnano.11.125

• ), is the retardance of the material, relating stress and strain, and R is the indenter radius. The indentation and load are available from the force–distance curve, and an expression for can be easily derived for the Generalized Voigt or Maxwell models (Figure 1), whereby the constants of springs and

Extracting viscoelastic material parameters using an atomic force microscope and static force spectroscopy

• Cameron H. Parvini,
• M. A. S. R. Saadi and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2020, 11, 922–937, doi:10.3762/bjnano.11.77

• contact time is short. Therefore, while the solution form could use the creep compliance for fitting, it is more direct to use the material retardance. The creep compliance can be defined in terms of the applied stress σ(t), the strain ε(t), and the material retardance as: By taking the Laplace transform

• of Equation 2, rearranging, substituting the creep compliance relationship above, and taking the inverse Laplace transform, one arrives at the following result: Equation 5 allows for the straightforward definition of the retardance U(t) according to an appropriate material model. The convolution

• retardance can be derived, one can replace U(t − ζ) in the above equations to make an implicit assumption of how the material reacts to applied stress. Acquiring these relationships is generally done by taking the derivative of the creep compliance J(t) of the model, as the two quantities are related in

Remarkable electronic and optical anisotropy of layered 1T’-WTe₂ 2D materials

• Qiankun Zhang,
• Rongjie Zhang,
• Jiancui Chen,
• Wanfu Shen,
• Chunhua An,
• Xiaodong Hu,
• Mingli Dong,
• Jing Liu and
• Lianqing Zhu

Beilstein J. Nanotechnol. 2019, 10, 1745–1753, doi:10.3762/bjnano.10.170

• -symmetry 2D materials. In detail, when linearly polarized incident light impinges onto the 1T’-WTe2 crystal, as expected, an obvious phase retardance (Δδ) and reflectance difference (ΔR) appears between the two optical axes. The significant reflectance difference along the x- (Rx) and y- (Ry) axis is

Nanoscale optical and structural characterisation of silk

• Meguya Ryu,
• Reo Honda,
• Adrian Cernescu,
• Arturas Vailionis,
• Armandas Balčytis,
• Jitraporn Vongsvivut,
• Jing-Liang Li,
• Denver P. Linklater,
• Elena P. Ivanova,
• Vygantas Mizeikis,
• Mark J. Tobin,
• Junko Morikawa and
• Saulius Juodkazis

Beilstein J. Nanotechnol. 2019, 10, 922–929, doi:10.3762/bjnano.10.93

• were carried out for comparison at IR wavelengths of 2–10 μm using synchrotron radiation. A reliable distinction of transmission changes by only 1–2% as the anisotropy of amide bands was obtained from nanometer-thin slices of silk. Keywords: absorbance; anisotropy; retardance; silk; Introduction

• phase delay through the LC retarder is equal to the absolute value, but has an opposite sign through the silk fiber, the darkest (black) region is formed in the image at ca. 2.9 V (Figure 3a). For the thickness of fiber d = 48 μm and measured retardance, the birefringence Δn ≈ 4 × 10−3. This is an

• retardance of silk, d = 100 nm, has a birefringence of Δn = 4 × 10−3 at the non-absorbing vis–IR wavelengths. For example, the band at 3600 cm−1 (λ = 2.78 μm) resulted in ΔT = sin2(πΔnd/λ) = 2 × 10−5%, which was beyond the precision of measurements. Alternatively, the real part of the refractive index can be

Ultralight super-hydrophobic carbon aerogels based on cellulose nanofibers/poly(vinyl alcohol)/graphene oxide (CNFs/PVA/GO) for highly effective oil–water separation

• Zhaoyang Xu,
• Huan Zhou,
• Sicong Tan,
• Xiangdong Jiang,
• Weibing Wu,
• Jiangtao Shi and
• Peng Chen

Beilstein J. Nanotechnol. 2018, 9, 508–519, doi:10.3762/bjnano.9.49

• process of the carbon aerogels, the basic skeleton is retained, and most of the carbon aerogel did not burn at all, demonstrating their good flame retardance. As shown in Figure 10, the absorption capacity decreases from 75 to 38.2 g/g after 10 cycles, indicating the relatively stable recycling

• -hydrophobic CNF/PVA/GO carbon aerogels exhibited a high absorption capacity of up to 97 times their own weight for oils and organic solvents. Furthermore, the carbon aerogel also exhibited high absorption selectivity, good recyclability and flame retardance. Our findings are a proof-of-concept for the use of

Optical techniques for cervical neoplasia detection

• Tatiana Novikova

Beilstein J. Nanotechnol. 2017, 8, 1844–1862, doi:10.3762/bjnano.8.186

• . Finally, the scalar values of depolarization, retardance and diattenuation, as well as the orientation of the optical axes of the retarder and the diattenuator can be obtained from the matrices MΔ, MR, and MD. Strictly speaking, these parameters represent a set of “effective” optical markers of tissue. Lu

• –Chipman decomposition implies a sequential order of elementary polarimetric properties along the trajectory of the probing beam, whereas these polarimetric properties can be mixed within the volume of tissue. Nevertheless, these effective values of depolarization and retardance are found to be the

• values of scalar retardance drop in stromal areas adjacent to neoplastic epithelium. It can be explained by the structural reorganization of the extra-cellular collagen matrix accompanying early precancerous modifications of the epithelium [31][32]. The observed increase in depolarization power in